The need for this invention arose from problems of buffer current drain. In conventional input buffers (M3/M6), the DC supply current increases dramatically as the supply voltage increases. Specifically, the bias current is proportional to the square of the supply voltage impressed across a CMOS integrated circuit (IC). Accordingly, when large supply voltages are supplied to facilitate large signal output swings, the CMOS IC consumes a great deal of power.
The instant invention solves the problem by current mirror biasing via a biasing resistor and capacitively coupling the buffer output devices. As a result, bias current only goes up linearly with changes in supply voltage. Thus, a significant current savings is achieved. Moreover, a significantly lower IC operating temperature is attained.
This invention represents a significant advance over the prior art and over this technical field by providing a current-saving CMOS signal input buffer.